Method of making electrical condensers



Jan. 3, 1933. w. scHl-:PPMANN METHOD OF MAKING ELECTRICAL CONDENSERS Filed March 18. 193C HVENTOR UHIhem Scheppmann FTTOHH EY Patented Jan. 3, 1933 UNITED STATES 'Y PATENT OFFICE 'WILHELM SCHEPMANN, OF BERLIN-TEMPELHOF, GERMANY, ASSIGNOR TO C. LORENZ,

A. G.,OF BERLIN-TEMPELHOF, GERMANY METHOD OF MAKING ELECTRICAL CONDENSERS Application filed March 18, 1930, Serial No. 436,775, and in Germany May 25, 1929.

My invention relates to a method of making electrical condensers, particularly of small capacity, which is economical and oiers increased dependability of servlce.

The invention is more particularly directed to the manufacture of condensers of small capacity such as are commonly used 1n radlo Ireceiving sets. According to the established practice for making such condenser-s, 1t 1s customary to stack upon each other alternate sheets of insulating-material and conducting material or to wind strips of conducting material with interposed strips of dielectric material to a compact unit. Condensers of this kind, however, possess the disadvantage that it is necessary to provide means to keep the assembled sheets tightly together 1n order to prevent displacement of the dielectrlc 1n respect to the condenser armatures. Such displacement would entail changes in the capacity and is furthermore liable to give rise to flows in the dielectric and to ashort c1rcu1t of the condenser.

I overcome these drawbacks by the novel method of making condensers as described by the present invention. To obtain this object, I propose to use a continuous strip of dielectric such as paper, Celluloid, rubber, or what is known on the market as cellopl'iase and the like, which is coated on both sides with a metallic layer. This strip is then sliced into a number of units corresponding to the size of the individual capacities. In order to prevent an increase of the leakage ath from one condenser armature across the edge of the dielectric to the other armature caused by the cutting or slicing operation, a number of transverse sections at definite 1n- 40 tervals of the continuous strip are left free v from metallic coating as will be described in more detail.

Reference is made in the following description to the accompanying drawing, of which Figure 1 shows a strip of dielectric material provided with metallic coatings in accordance with my invention. Y

Figure 2 is a cross-section through a completed condenser as shown by Figure 3. 5 v Figure 3 shows a finished individual condenser unit as sliced from a strip as shown by Figure l, and

Figure 4 illustrates a single clamp which may be used for a condenser, as shown in Figure 3.

Similar reference numbers refer to identical parts throughout the diferent views of the drawing.

The dielectric strip l is coated on both sides by conducting layers 2 and 3 respectively. Such coating may be carried out according to any one of the well-known processes, such as, for instance, by means of a spraying process orby a so-callcd cathode disintegration process, or by means of an ele'ctrolytic process. The conducting layers are not applied over the entire surface of the dielectric, but a proper margin 6 is left free at opposite ends respectively, as seen from Figure 2. Furthermore, a number of transverse sections 5 are also left free from the metallic deposit at del'inite intervals corresponding to theV desired capacity of the individual condenser units. These free sections and the margins 6 may be obtained by placing a stencil upon the dielectric sheetduring the coating operation covering the space of the sections 5 as Well as of the margin 6 and preventing a deposit of conducting material at these places.

Afterwards, the strip thus obtained is sliced across the sections 5 as indicated by dotted lines at A-A in Figure l and a corresponding number of individual condenser units obtained. The metallic layers 2 and 3 may then be connected in the usual manner to a clamp 6 and the whole surrounded by a casing 7 in order to protect the condenser against atmospheric inliuences. Figure t is a. simple kind of clamp to be used in connection with the invention as shown, which consists of a connecting terminal 6 provided with flaps 8 which may be turned over by 180 degrees and bent around the edges of the condenser.

The further advantage of this method consists in that it is possible to use a very thin sheet of dielectric which insures the desired amount of capacity usually used in receiving sets by a condenser having two armatures only, such as illustrated. The providing of free sections 5 has the advantage that during 10o the slicing operation only insulating material is cut and not the metallic coating, "hich makes it impossible for metallic partiel s to be drawn by the cutting tool around the edge 5 of the insulating material, thus decreasing the creeping path between the condenser armatures and creating a defective condenser. Althou h I have disclosed my invention with speclic reference to the showing of the l0 drawing presented for pur ose of illustration, I wish 1t to be understoo that other forms are possible to practice the invention in conformity withl the scope of the appended claims. What I claim is: l

1. The method of manufacturing electrical condensers which consists in coating a continuous strip of dielectric material at both sides with a metallic layer with transverse v sections at definite intervals left free from said coating and slicing said strips across said free sections.`

2.. The method of manufacturing electrical condensers which consists in coating a continuous strip of dielectric material at both sides with a metallic layer, with a margin of both of the layers at opposite ends and a number of transverse sections at definite in- .tervals left free from said coating, and aft- 80 erwards slicing said strip into individual unitsacross said free sections..

3. The method of manufacturing electrical condensers which consists in coating a continuous strip of dielectric material at both i sides with -a metallic layer by an electrolytic rocess with transverse sections at definite intervals left free from said coating, and slicin said strip across said free sections.

4. he method of manufacturing electrical condensers which consists in coating a continuous stripv of dielectric material at both sides with a metallic layer by an electrol ic process, with a. margin of both of sai layers at opposite yends and a number s of transverse sections at definite intervals left free from said coating, and afterwards slicing said strip into individual units across said transverse sections.

5. The method of manufacturing electri: cal condensers which consists in applyin to a continuous strip of dielectric materia at both sides 'a metallic layer'with transverse sections at definite intervals left free from said metallic layer and slicing said strips across saidfree sections.

In testimony whereof I aiix my signature.

`VVILHILLM SCI-IEPPMANN. 

